IgG4-related disease

Immunoglobulin G4-related disease, or IgG4-RD, is a rare autoimmune condition where the immune system mistakenly attacks one or more healthy organs. It often shows up as tumor-like masses, enlarged organs, or painless swelling. If left untreated, the inflammation from IgG4-RD can lead to permanent damage. The disease is more common in middle-aged to older adults and in people assigned male at birth, but it can affect anyone, including children.

IgG4-RD is treated by specialists like rheumatologists, immunologists, and other providers experienced in autoimmune and inflammatory diseases. At Penn Medicine, our team has deep experience caring for people with rare conditions like IgG4-RD, and many travel from across the nation to benefit from our expertise.

You can have IgG4-RD for months or even years without symptoms before it is diagnosed. This delay can lead to organ damage even while you feel well. Sometimes the disease can mimic cancer, appearing as a mass.

When symptoms do occur, they vary widely from person to person. Because the disease can affect one or several organs at the same time, or at different times, it can appear in many ways, including:

• Swelling of the face or other areas
• Eye discomfort or bulging of one or both eyes (proptosis)
• Abdominal pain or blocked urine flow
• Yellow skin or eyes (jaundice)

Many people with IgG4-RD are first diagnosed with another condition that seems to affect just one organ. Over time, specialists discovered that several of these conditions share the same immune system problem and actually fall under the umbrella of IgG4-RD.

While research is ongoing, these diseases are now recognized as forms of IgG4-RD:

• Type 1 autoimmune pancreatitis
• Interstitial nephritis
• Riedel’s thyroiditis
• Mikulicz’s disease
• Küttner’s tumor
• Mediastinal fibrosis
• Retroperitoneal fibrosis

The exact cause of IgG4-related disease isn’t clear, but researchers believe it involves a problem with the immune system. In IgG4-RD, the body makes too many IgG4 antibodies, and certain immune cells build up in affected organs. This causes swelling, irritation, and scar tissue that can make the organ stiff and less able to work.

While there’s no cure for IgG4-RD, it’s often very treatable. Treatment may start with a steroid like prednisone to quickly calm inflammation. Your provider may recommend other immune-suppressing medicines, including targeted treatments like monoclonal antibodies that focus on specific immune cells.

The goal is to stop the disease from progressing, put it into remission, and keep it there to help prevent scarring and long-term organ damage. Because these medicines can also lower your body’s ability to fight infections, your care team will watch you closely and adjust your treatment to balance keeping the disease under control with keeping you healthy.

For many people, getting the right diagnosis for IgG4-RD can be a long and frustrating journey since it can look like other illnesses and organ damage can be serious. That’s why it’s important to work with a provider who understands the disease and can monitor you closely. At Penn Medicine, our specialists have experience with new and evolving conditions like IgG4-RD, and know how to respond quickly to protect your health.

Because IgG4-RD can affect multiple organs, our experts from different specialties work together to create a tailored treatment plan, carefully monitoring your organs and overall health while supporting you every step of the way.